Low noise producing lawn mower blade

Abstract

A lawn mower blade includes a leading flat portion, at each of its opposite ends, sharpened to define a cutting edge and a trailing vane is joined to and is angled upwardly in trailing relationship to each flat portion. In one embodiment, the vanes are each in the form of a lift wing and perforations or holes are located in the leading flat portion ahead of the lift wing and provide air pressure relief passages. In another embodiment the vanes include lift wings and bagging paddles joined to the lift wings and including second leading flat portions to which trailing fins are joined. The second leading flat portion is either recessed to form a space between outer end portions of the fin and flat portion or is perforated to provide air pressure relief passages.

I claim: 
     
       1. In a rotary mower blade adapted for rotation about an upright axis and having opposite end portions each including a first leading flat portion sharpened to define a cutting edge and a trailing lift wing joined to and angled upwardly in trailing relationship to the leading flat portion, the improvement comprising: a bagging paddle joined to each lift wing; each paddle including a second leading flat portion joined to the lift wing and a trailing fin angled upwardly in trailing relationship to the second leading flat portion; and air pressure relief means defined in the second leading flat portion ahead of the fin. 
     
     
       2. The rotary mower blade defined in claim 1 wherein the second leading flat portion of each end portion is recessed inwardly toward a central location of the blade spaced equidistant from the opposite end portions thereof relative to an imaginary line joining respective outermost surfaces of the lift wing and the fin to thereby define at least a portion of said air pressure relief means. 
     
     
       3. The rotary mower blade defined in claim 1 wherein a plurality of perforations are located in the second leading flat portion to thereby define at least a portion of said air pressure relief means. 
     
     
       4. The rotary mower blade defined in claim 1 wherein an outermost surface of the cutting edge of each of the opposite end portions is spaced outwardly from the central location a distance greater than the outermost surfaces of the lift wing and fin to thereby define a further portion of the pressure relief means. 
     
     
       5. The rotary mower blade defined in claim 2 wherein an outermost surface of the cutting edge of each of the opposite end portions is spaced outwardly from the central location a distance greater than the outermost surfaces of the lift wing and fin to thereby define a further portion of the pressure relief means. 
     
     
       6. In an elongate mower blade having a mounting portion located centrally between opposite ends thereof, leading cutting edge portions at opposite ends thereof located for sweeping through a common plane and trailing vanes respectively located behind the cutting edge portions and inclined upwardly from the plane and terminating in trailing edge portions, the improvement comprising: an air pressure relief notch formed between the cutting edge portion and trailing vane at each end of the blade and extending inwardly toward the mounting portion from an outermost end surface of the blade considered relative to the mounting portion. 
     
     
       7. The mower blade defined in claim 6 wherein the extent of each notch inwardly toward the mounting portion of the blade is less than the extent of the adjacent upwardly inclined e.